Sheppard J then turned (at 6) to the question of the meaning of a number of the words and expressions used in the advertisement complained about in that case. For the purpose of resolving that question, Sheppard J relied on "the ordinary meaning which they [that is, the words and expressions] have when they are used in the general run of English expression whether written or oral", as opposed to some technical meaning which they might also bear. So far as concerned two of the words which had been used in the advertisement, namely, "evidence" and "disease", Sheppard J considered that readers of the advertisement might reasonably have taken from the use of each of those words either one of two definitions of it appearing in the Oxford English Dictionary (2nd ed.) ("the OED"); he therefore considered each of those possible meanings of each word when determining whether the advertisement contravened subs 52(1) of the Act (see at 6-7 and 10).
21. Foster J (at 26) rejected any notion:
"... that a court dealing with a claim under s 52 of the Act based on an alleged misleading or deceptive statement must necessarily make, as it were, a preliminary determination of its own as to whether the statement complained of is to be classified as one of fact or one of opinion: that is to say, a determination without regard to what might be the view of the class of readers, or some significant section of it, to which the statement is directed. It is the court's perception of the character which those readers would accord to the statement which is, at all stages, the determining factor."
His Honour then rejected (at 26-27) a somewhat different submission which had been made before the Full Court by the Tobacco Institute, namely, that the relevant advertisement "was so obviously a statement of opinion and not of fact that only the most stupid of readers, whose interests, on the weight of authority, fall outside the protective circle of s 52, would have read it as a statement of fact". In doing so, his Honour said,
"Whilst, no doubt, a section of the newspaper reading public might regard the [advertisement] as merely an expression of ... opinion, the remaining section which, in my view, would be of substantial size, would see it as a statement of fact. This, of course, is sufficient to require that it be accepted as a statement of fact when considering whether its publication constituted a breach of s 52 of the Act. "
Foster J also made a number of references in his reasons for judgment to the process of determining the meaning of particular words and phrases in the advertisement. He referred (at 29) to "the question of what meanings could reasonably be attributed to the [advertisement] by the hypothetical lay reader"; he referred (at 31) to the fact that a significant number of readers would have understood a particular phrase in the advertisement in a particular sense and then continued, "It may have been capable of bearing other meanings, but in the type of inquiry necessarily required by s 52, that is beside the point"; he rejected (also at 31) the notion that the word "evidence" appearing in the advertisement should be construed according to the "meaning that it may have for persons trained in the disciplines of law or science"; and he rejected (at 32) the notion that the word "cause" appearing in the advertisement should be construed according to the meaning attributed to it in "scientific, philosophical or legal discussion".
22. Hill J referred (at 44-45) to two "separate, albeit related" questions arising in the appeal before the Court, with which questions it was necessary to deal: "The first is whether the ... advertisement ... should be seen to be a statement by the appellant of its opinion.... The second is the meaning of the words used in the advertisement".
23. As to what he had described as the first question, Hill J said (at 46) that "it must essentially be a question of fact whether a particular formulation of words expresses merely an opinion or a statement of fact". In the resolution of that question, his Honour said (at 46-47),
"[T]he reader's perception of the maker's intention ... will ordinarily be the significant matter. The question will generally be resolved by looking to the persons to whom the statement was directed and asking whether any members of that class of persons would reasonably understand the statement to be one of fact or of opinion.
Where, as here, the statement is directed to the public at large, it must be borne in mind that the class of persons will include the intelligent and the less intelligent, the informed and the less informed. The fact that some members of the class may perceive the statement as one of opinion will not avail a respondent if a not insignificant class of persons could reasonably be expected to perceive it as a statement of fact.
...
[T]he advertisement is capable of being perceived as a statement of fact by a not insignificant section of the public, even if some members of the public, well informed, would not so see it.
...
[T]he advertisement is reasonably open to be interpreted either as a statement of opinion ... or as a statement of fact.... If the former, it will be misleading, or will be likely to be misleading, if the [applicant] has shown that the view was not bona fide held by the [respondent] (and this is not suggested) or that the view was not reasonably capable of being held. If the latter, the [advertisement] will be misleading or likely to be misleading (ie to lead the reader into error) if the statement of fact made in it be false."
24. As to what he had described as the second question, Hill J said (at 48; 50),
"The elucidation of the meaning of the words used in [the advertisement] is, like the question whether the [advertisement] is a statement of fact or opinion, made more difficult because more than one possible construction may be adopted by a particular reader....
...
Where, as in the present case, the advertisement is capable of more than one meaning, the question of whether the conduct of placing the advertisement in a newspaper is misleading or deceptive conduct must be tested against each meaning which is reasonably open. This is perhaps but another way of saying that the advertisement will be misleading or likely to mislead or deceive if any reasonable interpretation of it would lead a member of the class, who can be expected to read it, into error...."
25. While there were differences of expression among the three Judges who decided the Tobacco Institute appeal and, further, while there are differences of expression between all of them and what I have said above, I consider that the passages which I have set out above from their Honours' reasons for judgment in that appeal support, in substance, the correctness of the approach to which I have referred at [17] and [18] above.